1. Field of the Invention
This invention relates to antenna systems; and more particularly, to such antenna systems configured for with a novel frequency tuning and matching architecture.
2. Description of the Related Art
Active antennas are currently used in a wide variety of applications and are configured to performs various functions, including: (i) altering the radiation pattern; (ii) varying an electrical length of radiating elements; (iii) varying antenna impedance; (iv) shifting the antenna resonance; (v) compensating for antenna loading conditions (ex: device against the head and/or hand); (vi) increasing isolation in between antennas in MIMO systems; and (vii) decreasing the correlation coefficient within antennas, phase shifters and other complex features.
Of concern in the instant disclosure is the need to vary the antenna resonance and provide a corresponding match for a particular ground plane size and electromagnetic environment using commercially available components.
Working within newer LTE bands, including the frequencies around 700 MHz, the antenna design process is complicated due to the physical space permitted for the antenna being significantly less than the physical space needed for a conductor. Thus, the antenna is generally required to be electrically small. This results in difficulties to achieve a resonance and then the required matching to comply with the required bandwidth.
There is a significant need to develop improved antenna systems and related schemes for obtaining resonance and matching with small ground plane sizes.